Yes, they have had a visor feature for a long time actually. I'm not on my mac right now and i'm not 100% sure if this link is accurate anymore. But it's under the keyboard shortcuts or profile settings. It is not enabled by default, and you can create a new hotkey profile with more transparency or whatever,
http://fokkezb.nl/2014/10/29/using-iterm2s-improved-visor/